An increasing number of wireless communication standards as applied to portable devices and a trend towards smaller, slimmer and lighter portable devices may cause major design challenges for antenna or antennas (hereinafter referred to as antenna in this document). The antenna represents a category of components that may fundamentally differ from other components in the portable device. For example, the antenna may be configured to efficiently radiate in free space, whereas the other components are more or less isolated from their surroundings.
Antennas operating at millimeter wave (mm-wave) frequencies—for high data rate short range links—are expected to gain popularity in the near future. One example of such an application or standard is called WiGig (Wireless Gigabit per Second), which operates at the ISM frequency band at around 60 GHz. In addition, utilization of the mm-wave radio systems is projected to play a role on future standards such as 5G cellular radio. Typically, these short range mm-wave radio systems require an unobstructed line-of-sight (LOS) between a transmitter and a receiving antenna for highest datarate at lowest power consumption. Such systems may also operate in non-line-of-sight (NLOS) configuration using signal reflection from surrounding objects. A goal of the WiGig standard is to enable NLOS transmission using wireless links. With the LOS requirement, an orientation of the transmitting and receiving antennas may require their respective main lobe to face each other for maximum radio link efficiency. Single element antenna designs such as those used in mobile devices such as laptop computers, tablets, smartphones, etc. are limited in coverage and further exhibit low gains at mm-wave operating frequencies.